> -----Original Message----- > From: Vinod Koul [mailto:vinod.koul@xxxxxxxxxx] > Sent: 2018年5月21日 17:09 > To: Wen He <wen.he_1@xxxxxxx> > Cc: dmaengine@xxxxxxxxxxxxxxx; robh+dt@xxxxxxxxxx; > devicetree@xxxxxxxxxxxxxxx; Leo Li <leoyang.li@xxxxxxx>; Jiafei Pan > <jiafei.pan@xxxxxxx>; Jiaheng Fan <jiaheng.fan@xxxxxxx> > Subject: Re: [v4 2/6] dmaengine: fsl-qdma: Add qDMA controller driver for > Layerscape SoCs > > On 18-05-18, 10:04, Wen He wrote: > > > > > > > +u64 pre_addr, pre_queue; > > > > > > > > > > why do we have a global? > > > > > > > > Let's us see qDMA that how is works? > > > > > > > > First, the status notification for DMA jobs are reported back to > > > > the status > > > queue. > > > > Status information is carried within the command descriptor > > > > status/command field, bits 120-127. The command descriptor dequeue > > > > pointer advances only after the transaction has completed and the > > > > status > > > information field has been updated. > > > > > > > > Then, the command descriptor address field wiil pointer to the > > > > command descriptor in its original format. It is the responsibity > > > > of the address of the status queue consumer to deallocate buffers > > > > as needed when > > > the command descriptor address pointer is non-zero. > > > > > > > > More details of the Status Queue can be found in QorIQ Layerscape > > > > Soc > > > datasheet. > > > > > > > > So, these variable is used to record latest value that command > > > > descriptor queue and status field. > > > > > > > > Every time variables value is zero when set these variable to > > > > local, that's not > > > what I want. > > > > > > Why not store them in driver context? > > > > > > > okay, maybe I should remove these variable to private struct? > > Yes that would be better > > > > > > > + memset(sg_block->virt_addr, 0, > > > > > > + FSL_QDMA_EXPECT_SG_ENTRY_NUM * > 16); > > > > > > > > > > why FSL_QDMA_EXPECT_SG_ENTRY_NUM * 16? and not what you > > > allocated? > > > > > > > > > > > > > see line 497. > > > > The sg_pool buffer size created is FSL_QDMA_EXPECT_SG_ENTRY_NUM > * > > > 16. > > > > > > Please document this > > > > > Add comment to this? > > yup, explaining where 16 is coming from got it, thanks for your review and will be next version fix it. Best Regards, Wen > -- > ~Vinod ?韬{.n?????%??檩??w?{.n????z谵{???塄}?财??j:+v?? ? ???2??璀??摺?囤??z夸z罐?+?????w棹f
